Atanu Adhvaryu

Epoxidized soybean oil as a potential source of high-temperature lubricants

Development and application of biocompatible lubricants are increasing daily as a result of stringent regulations imposed on mineral oil-based lubricants with their non-biodegradable toxic wastes. Before consumer acceptance of vegetable oil-based lubricants, they must overcome certain poor performance characteristics such as thermal and oxidative instabilities. This work demonstrates the improved performance of epoxidized soybean oil (ESBO) over soybean oil (SBO) and genetically modified high oleic soybean oil (HOSBO) in certain high temperature lubricant application. We validated the thermal and deposit forming tendencies of these oils using micro-oxidation and differential scanning calorimetry in conjunction with identification of oxidized products by infrared spectroscopy and also discussed the function of a phenolic antioxidant in these oils. Boundary lubrication properties under high load and low speed were determined and the variations explained based on the structural differences of these vegetable oils.

Lubricant base stock potential of chemically modified vegetable oils.

The environment must be protected against pollution caused by lubricants based on petroleum oils. The pollution problem is so severe that approximately 50% of all lubricants sold worldwide end up in the environment via volatility, spills, or total loss applications. This threat to the environment can be avoided by either preventing undesirable losses, reclaiming and recycling mineral oil lubricants, or using environmentally friendly lubricants. Vegetable oils are recognized as rapidly biodegradable and are thus promising candidates as base fluids in environment friendly lubricants. Lubricants based on vegetable oils display excellent tribological properties, high viscosity indices, and flash points. To compete with mineral-oil-based lubricants, some of their inherent disadvantages, such as poor oxidation and low-temperature stability, must be corrected. One way to address these problems is chemical modification of vegetable oils at the sites of unsaturation. After a one-step chemical modification, the chemically modified soybean oil derivatives were studied for thermo-oxidative stability using pressurized differential scanning calorimetry and a thin-film micro-oxidation test, low-temperature fluid properties using pour-point measurements, and friction-wear properties using four-ball and ball-on-disk configurations. The lubricants formulated with chemically modified soybean oil derivatives exhibit superior low-temperature flow properties, improved thermo-oxidative stability, and better friction and wear properties. The chemically modified soybean oil derivatives having diester substitution at the sites of unsaturation have potential in the formulation of industrial lubricants.

One-pot synthesis of chemically modified vegetable oils.

Vegetable oils are promising candidates as substitutes for petroleum base oils in lubricant applications, such as total loss lubrication, military applications, and outdoor activities. Although vegetable oils have some advantages, they also have poor oxidation and low temperature stability. One of the ways to address these issues is chemical modification of fatty acid chain of triglyceride. We report a one-pot synthesis of a novel class of chemically modified vegetable oils from epoxidized triacylglycerols and various anhydrides. In an anhydrous solvent, boron trifluoride etherate is used as catalyst to simultaneously open the oxirane ring and activate the anhydride. The reaction was monitored and products confirmed by NMR, FTIR, GPC, and TGA analysis. Experimental conditions were optimized for research quantity and laboratory scale-up (up to 4 lbs). The resultant acyl derivatives of vegetable oil, having diester substitution at the sites of unsaturation, have potential in formulation of industrial fluids such as hydraulic fluids, lubricants, and metal working fluids.

Wax appearance temperatures of vegetable oils determined by differential scanning calorimetry: effect of triacylglycerol structure and its modification

Abstract Crystallization and wax appearance temperatures of a series of vegetable oils (natural, genetically and chemically modified) were studied using differential scanning calorimetry (DSC). The fatty acid chains of a triacylglycerol molecule have a bend ‘tuning fork’ conformation and undergo molecular stacking during the cooling process. Wax crystallization at low temperature is controlled by steric and geometrical constrains in these molecules. This study describes an approach to quantify and predict wax appearance temperature of vegetable oils based on the statistical analysis of DSC and NMR data. A molecular modeling program was used to design triacylglycerol molecules with different fatty acid (e.g. oleic and linoleic) chains to illustrate their effect on the crystallization process. Effect of pour point depressant (PPD) additives on vegetable oil crystallization is also discussed.

Thermo-oxidative stability studies on some new generation API group II and III base oils

Abstract Due to the increasing demand for highly saturated (group II and III) base oils for use in specialty lubricant application, it is necessary to obtain a clear picture of the base oil molecular distribution. These oils are more stable to oxidation and exhibit superior performance-based characteristics as compared with group I type base oils. With the aromatic content reaching a minimum value, saturated molecules control most of the physical properties in these oils. Molecular structure based characterization developed for conventionally refined base oils will be inadequate to address all the structural diversities of these base fluids. In this study, results from thin film micro oxidation (TFMO) and pressure differential scanning calorimetry (PDSC) were discussed in terms of the quantitative 13 C NMR (inverse gated, CSE, GASPE) data. Correlations obtained with physical properties (e.g. viscosity), oxidation (evaporation, insoluble deposit) and structural data indicate the significance of base oils saturate hydrocarbon structures in influencing most of the performance properties.

Chemical Modification of Vegetable Oils for Lubricant Basestocks

Use of vegetable oil based lubricants will reduce petroleum imports and have a favorable environmental impact. The vegetable oils are derived from a renewable sources, biodegradable, non-toxic, possess high flash points and have low volatility. Inadequate oxidative stability and poor low-temperature properties of vegetable oils limit their utilization as lubricants. In this study, we report the development of chemical modification methods to improve these functional properties. The resultant vegetable oil derivatives having diester substitution at the sites of unsaturation shows comparable properties to mineral base fluids.© 2003 ASME